What is the basic function of a relay in electrical systems?

The basic function of a relay in electrical systems is to control a high-power circuit with a low-power signal. Relays are electromagnetic switches that use a small current flowing through a coil to create a magnetic field, which then activates a switch that can control a much larger current. This allows for the control of high-power devices while using low-power signals, making them essential for the operation of various electrical systems, including automation and safety controls.

In practical terms, this means that a relay can act as an intermediary that allows a low-voltage control circuit to influence a high-voltage load circuit without needing operators or systems to directly manage the higher voltage. This separation enhances safety and protects sensitive control circuits from high currents.

The other options do not accurately represent the primary function of a relay; relays are not designed to increase power supply, measure voltage levels, or directly connect loads to power sources without a control mechanism. These functions are typical of different components in electrical systems and highlight the specific application and importance of relays in managing electrical power effectively.